Air conditioning



A 731945" s. w. ANDERSSON AIR CONDITIONING Filed Aug. 14, 1941. 6 SheetsSheet 1 7, 5 s. w. E. ANDERSSON ,381,4 7

AIR CONDITIONING Filed Aug. 14, 1941 6 sheets sheet 2 1 4- 1 viii.

- m0 mg INVENTOR.

' BY W Zurroxyn g 1945 s. w. E. ANDERSSON AIR CONDITIONING Filed Aug. 14, 1941 6 Sheets-Sheet 3 INVENTOR.

s. w. E..ANDERs'soN AIR CONDITIONING Filed Aug. 14, 1941 e sheets-sheet 4 J m ZMM Aug. 7, 1945.

BY RT TO RIVEY BL awn? M0 706 g s. w. E. ANDERSSON 2,381,427

AIR CONDITIONING Filed Aug. 14, 1941 6 Sheets-Sheet 5 INVENTOR.

Aug. 7, 1945. s. w. E. ANDERSSON 2,331,427

AIR CONDITIONING Filed Aug. 14, 1941 6 Sheets-Sheet 6 INVENTOR fia' ATTORNEY Patented Aug. 7, 1945 UNl'lED' STATES orrlcai AIR CONDITIONING Sven W. E. Andersson, Evansville, Ind., assignor to Servel, Inc., New of Delaware York, N. Y,., a corporation v Amman! gust 14, 41. Serial No. 406.77%"

. 31 Claims.

This invention relates to air conditioning and is,

especially concerned with control of air conditioning systems. More particularly, the invention relates to control of air conditioning systems arranged-to heat and humidify air during periods of cold weather, to coal and dehumidify air during periods of warm weather, and to provide ventilation alone when desired. In the illustrated em- \bodiment which discloses one manner of practicing the invention, the control is shown in connection with a combined heating, cooling and ventilating system in which cooling of air is efiected by refrigeration apparatus of the kind operated by heat.

The control provided is' of the proportionin type in which heating or cooling of air is regulated by steps or stages by controlling in steps or stages the supply of heat to the air .conditioning system both during the heating and cooling periods.

supply of fuel to burner structure arrangedto heat a boiler in which steam is produced, and utilizing.

the steam as a medium either to cause heating of air by a heater orto effect heating of a generator or heat receiving D li of refrigeration apparatus to cause cooling of air by a cooling element.

The control which is located so that it will be affected by the ambient temperature'in an enclosure in which the air is to be conditioned. The thermostat device serves as a part of an electrical system to which is connected the electrical apparatus associated with the air conditioning system. The electrical apparatus includes electromagnetically operated valves for controlling the fuel supply, electric motors foroperating auxiliary equipment associated with the airconditioning system, relays for completingand opening the circuits in which-the electric motors areconnected, and safety switches which become effective to protectthe air conditioning system when faulty operation occurs. In

. regulating the heat supply by steps or stages in 45, andvvenmatmg system;-

Fig. 2 is a vertical sectional view of the control the manner referred to above, the component and subsidiary parts of the control are so correlated and-interrelated that many. parts can be utilized when the air conditioning system is either oper- I 'ating to heat or cool air or simply provide ventilation.

The thermostat device. includes three control switches each operable to-initiate a succession of .events depending upon whether heating or cooling of air or simply ventilating will provide the best comfort conditions. The electrical circuits 55 In the embodiment disclosed this is accomplished by contr lIing in steps stages the and responsiveness have comprises a thermostat device 35 objects and embodied in the control are so interrelated that even when the controlswitches are improperly manipulated, as when the. switches are operated in an attempt to effect heating and cooling of air 5 at the same time, the air conditioning system will not respond to such improper handling of the control switches and will remain ineffective to cause either heating or cooling of air without endangering 0r impairing" the normal function of any v part of the control. Provision is also made so that continuous or constant ventilation can be obtained during the periods when the air conditioning system is rendered operable to heat or cool air and ordinarily shuts down when the desired air temperature is reached.

it is desired to point out at the outset, before proceeding with a more detailed description of the invention, that the thermostat device is not only dependable in operation but is extremely sensitive 0 and, responds rapidly to change of air temperature., The factors of dependability, sensitivity thermostat device provided by constructing and arranging the parts so that no one part W111 be subjected to strains or excessive force, and by employing an expansible n d thermostat 1n 1 which all parts are continuously heated except a thin walled thermal sensitive element which is the-coldest part and arranged to be readily influenced byair temperature. I

The novel features which are believed to be illustrated in Fig. 1;

Fig.- 3 is a horizontal sectional view, taken at line 3-3 of Fig. 2, to illustrate more clearly the swinging gate embodied in the control;

' Fig. 4 is a front 'view of the control, taken at line 4-4. of Fig. .2, with the front cover plate in Fig. 1 removed and partly in section,to illustrate parts of the control more clearly;

been obtained in the Fig. 5 is a vertical sectional view, taken at line water is delivered to nozzle 25. thro 26 from a suitable source of supply,

55 of Fig. 2, to illustrate more clearly the swinging gate and associated parts of the control;

Fig. 6 is a side view, taken at line |i6 of Fig. 5, with the control partly broken away and in section, to illustrate parts thereof more clearly;

Fig. 7 is a fragmentary sectional view, taken at lines 1'! of Figs. 6 and 8, to illustrate the switch structure embodied in the control;

Fig. 8 is a fragmentary sectional view, taken at line 88 of Fig. 7, to illustrate the. switch structure more clearly;

Fig. 9 is a fragmentary rear view of the control, taken at line 9-..9 of'Fig. 2, showing the circuit connecting panel to illustrate more clearly the association of the control and several electrical circuits controlled thereby;

Fig. 10 is a view diagrammatically illustrating the association of the manual switches at the top of the thermostat control, the thermostatically operated switches mounted within the control casing, and the circuit connecting panel;

Fig. 11 is a view diagrammatically illustrating the several electrical circuits controlled by th'e 7 thermostat control and the connection of these circuits tothe circuit connecting panel;

Fig. 12 is a view diagrammatically illustrating a combined heating, cooling and ventilating system, the auxiliary equipment for the system, and control devices and safety features with which are associated the several electrical circuits controlled by the thermostat control, as shown in Fig. 11; and

heated by heater I 9.

-. I The treated air, which is either heated or Fig. 13 i a. view diagrammatically illustrating the refrigeration apparatus of which parts are shown in Fig. 12.

TIONING SYSTEM, SAFETY DEVICES.

Referring to Fig, 12, a combined heating and cooling system is arranged in a duct system DESCRIPTION OF AIR CONDI AUXILIARY EQUIPMENT AND.

' through which air is drawn from an enclosure l4 "cooled, as explained above, is discharged by blower 2| through conduit 22 to the enclosure 14. When ventilating alone is desired, the blower 2| can be operated with both the cooling element I1 and heater I9 inoperative, so that air will be drawn from the enclosure l4 past filter I6 and then returned to the enclosure through duct 22. The blower 2| is connected to a suitable electric motor 28 which is indicated in dotted lines in Fig. 12. The cooling element l1 form part of refrigeration apparatus of a two-pressure absorption type and like that desscribed in application Serial No. 239,762 of A. R. Thomas and P. P. Anderson, Jr., filed November 10, 1938, now Patent No. 2,282,503 granted May 12, 1942. In a system of this type liquid refrigerant, such as, for example, water, is introduced into the upper part of cooling element I1 from a condenser 29 through a path of flow including a conduit 30, as shown most clearly in Figs. 12 and 13. The liquid refrigerant evaporates in cooling element I 1 with consequent absorption of heat to produce a refrigerating or cooling effect to cool air drawn through duct I8, as explained above. The refrigerant, vapor formed in cooling element I1 .flows therefrom to an absorber 3| in which the vapor is absorbed into a liquid absorbent, such as, for example, lithium chloride solution. The absorption liquid enriched in refrigerant is conducted from absorber 3| to a generator 32 in a path of flow including a conduit l2, a first passage of heat exchanger I3, a conduit 33, vessel 34 and conduit 35. Within generator 32 are disposed a plurality of riser tubes enveloped by a ch'amber formed by the outer shell to which steam riser tubes into a vapor separator 38 and theme I8. Air is drawn through duct I8 and 2|) by a blower 2| from which .air'is discharged through a duct 22 to the enclosure l4.

Suitable dampers 23 are provided to control flow of air past cooling element l1, and similar dampers 24 are disposed in the lefthand arm of duct 2|1 to control flow of air past heater I9. When cooling element I1 is operative to effect cooling of air and dampers 23 are opened and dampers 24 are closed, cooling effect is transmitted to air flowing through duct' 18 from the enclosure I4 and duct I5. When heater I 9 is operative to effect heating of air and dampers 24 are opened and dampers 23 are closed, heating effect is transmitted to air flowing lr (111% 20 from the enclosure 14 and duct I3. I During the heating periods, water may be sprayedinto the air stream through a nozzle 25 located in the lefthand-arm of duct 20. The ugh a'conduit anelectrically operated solenoid valve 21 being connected in the conduit to control flow of water th'erethrough, manner proper humidiiication of air can '75 ing from absorption of refri absorbent, isgiven up to the cooling water. Theis supplied through a conduit 36 from a. boiler 31. The heating of the riser tubes by the steam causes refrigerant vapor to be expelled from the absorbent, the expelled vapor being effective to raise liquid absorbent by gas or vapor-lift action. The expelled vapor passes through the upper ends of I flows through a conduit 39 to condenser 29 in which the vapor is liquefied. The liquid refrigerant formed in condenser 29 flows through conduit 30 to the upper part of coolingelement I1, as explained above, to complete the refrigerating cycle. The raised absorption liquid from which refrigerant vapor hasbeen expelled is conducted from the upper part of generator 32 to absorber 3| to absorb refrigerant vapor, this ducted to the absorber in a path .of flow including a conduit 40, a. second passage dfheat exchanger I3 and conduit l I. l I

The disclosure in the aforementioned Thomas and Anderson application may be considered as being incorporated in this application, and, if desired, reference may be made thereto for a'detailed description of the refrigeration apparatus.

The condenser 29 and absorber 3| constitute heat rejecting parts ofthe refrigeration apparatus and are cooled. by a suitable cooling medium such as, for example, water, which is continuously circulated in a closed 0 spray-type cooling tower 4 I. conducted through a conduit tubes 43 within absorber 3I irouit through a The cooled water is 42 through banks of whereby heat, resultgerant va'por by liquid water is conducted from absorber 3| conduit 44 to condenser, 29 in which densation, resulting from condens frigerant vapor, is given up to the through a heat of conation of re-.

liquid being concooling water.

-' to generator .32 and to shut ofl. flow The water flows from condenser 29 through a conduit 45 to spray nozzles disposed in the upper part of the cooling tower 4|, one or which is iniiicated at 46 in Fig. 12. The water passing downward in tower 4i flows in intimate contact with an upwardlyflowing stream of air which is drawn through an inlet 41 by a fan 48, and exhausted motor 52. The steam boiler 31 is arranged to :be heated by v two burners 5 3.and 54 with the flames produced thereby adapted to pass into flues which are in g communication with heating-tubes disposed within the boiler.

the burners through conduits and 55 from a,

suitable source of supply, the flow of gas to the burners 53 and 54 being controlled by electricallyoperated solenoid valves 51 and 58,v respectively; Suitable tubing 89 is connected to conduit 55 and arranged to terminate in the vicinity of burners l3. and to provide pilot flames for igniting the gas discharged from the burners when the solenoid operated valves 51 and 58 are opened after a period when no gas flows to the burners. In addition to supplying steam from the boiler I (31 to generator 32 of the refrigeration apparatus,

steam is also supplied to heater i9 through a part of conduit 36 and a conduit 59. A steam Valve 0 is provided at the junction of conduits 36 and I3 to control the flow. of steam either to the generator 32 or to heater I9; The steam valve 60 is provided with a valve member which is movable between two positions by a two-position electrically operated control motor 6|. The two-posi- A combustible gas is delivered to to render cooling element i'l eflective to cool air, simultaneously with such operation or the control motor the dampers 24 are closed and dampers 23 ar opened.

In a combined heating and cooling system of the type described there is usually the require-' ment or a higher heat input to the boiler 31 during a heating period than during a cooling period.

In either period it is essential that the pressfire of the gas supplied to burners 53 and 54 be maintained substantially constant. v To this end a gas pressure regulator 61 is provided in gas conduit 55, and provision is made for utilizing the same regulator forboth'the heating and cooling periods. As diagrammatically illustrated in Fig.

' 12, this is accomplished by providing a spring 68 which acts against the regulator diaphragm,

the tension of which can be varied by a pin 69 capable of being moved downward by a lever 10 pivoted to a raised part of the regulator.

The lever 10 is also operated through a link II by the two-position control motor 6!. During the heating periods the lever 10 is in the lower position shown and acts on pin 69. Under these.

conditions gas is .supplied to burners 53 and 54 at a constant pressure dependent upon the extent .to which spring 68 is compressed by pin to. When the two-position control motor Si is caused to move to the position it assumes during a cooling period, the right hand end of lever 10 is raised and does not act on pin 69. Under these conditions gas is delivered at a lower constant pressure than during the heating period, whereby I heat is supplied at a lower rate to the boiler 3l by the burners 53 and 54.

The'condensate formed inheater i9 flows by gravity directly into the boiler 31 through a con-' duit I4 which extends below the boiler liquid level.

tion motor 8] may be of any well known type.

which, when caused to move from either one of its two positions to the other position, becomes 1 deenergized when the other position is reached. Asdiagrammatically illustrated in Fig. 12, a crank 42 provided on control motor 6| is operatively connected by'a link 63 to an angularly movable lever 44 which is capable of actuating steam valve ol. In the illustrated position of lever 64, it may "be assumed that the flow of steam to generator 32 is shut off and that all .of the steam can flow conduit 59 to heater l3. When the two'- '-positi on control motor -6l is caused to operate to move crank 62 from the position shown to its other position, as will be described presently, the

steam .valve is actuated to permit an of "the steam from boiler 31 to pass through conduit 36 of steam .to heater i3. 4

' At the same time that the two-position control motor operates steam valve 60, the dampers 22 and 24 are also actuated to direct air either past cooling element H or heater l9; This isvac- 2 complished by suitable mechanism which. operatively connects crank 62 and the dampers 2'3 .and I V As diagrammaticall illustrated in 12. this mechanism includes a 'bar 65 and a plurality of links 68 connecting the la'tter and the shafts upon which the dampers are journalled. In the assinned position or steam valve 60, with all oi. the steam b'eing supplied to heater l9 and the latter being operative to veii'ect heating'of air, dampers 23 are closed and dampers 24 are open. when the control motor BI is caused to operate Thecondensate formed in the steam chamber of generator 32 flows by gravity through conduit 13 to a condensate collection vessel I5. From vessel the condensate is returned through conduit I6 and the lower part of conduit 14 to the boiler 31 by a pump ll operated by an electric 'motor 18.. Although not illustrated, the boiler '31 is connected to a suitable source of water supply through which additional make-up water may be added from time to time, responsive to a liquid level control device .01 any well-known type, to keep the water at a desired level in the boiler 31.

When the water level becomes too low in boilerv 31 a safety device or low water cut-out relay 19 becomes effective to shut ofl? flowv oi' gas to burners 53 and 54, as will be described presently. As

best shown in Fig. 1'1,--the low water cut-out relay I3 is of an electric type in which an electric circuit is completed through the body of water in the boiler 31.

water in the boiler is utilized to complete an elec- Since a portion of the body of tric circuit, it will beapparent that when the water falls below a predetermined level the electric circuit will be opened.

"The steam boiler 31 operates substantially at atmospheric. pressure, there being a steam vent ii at the upper part of the steam chamber in generator 32 and a steam vent 8! for the heater N. The vent ll .15 connected to conduit 14 above v the liquid column formed in this circuit by the returning condensate. Since the condensate i'ormed in heater I8 trickles down along the in side walls of the upper part of conduit 14 and does not completely block ofl or seal the radiatorifrom the vent 3|, it will be clear that steam-can flow Irornthe heater l3 through the vent 8|.-

The vents 30 and 8| are joined to provide a common steam vent from which steam can pass from either heater I8 \or generator 82 to the atmosphere.

88, the expansible fluid thermostat becomes operative to cause opening of switch 84. As will be described presently, openingof switch 84 opens an electric circuit whichcauses electrically operatedsolenoid valves and 88 to shut ofi flow of gas to the burners 88 and 88 and also render inoperative the auxiliary equipment associated with the air conditioning system and described above.

The single-steam vent control just described takes the place of many controls that otherwise would be necessary to insure safe operation of the refrigeration system and also of the heating system. In the event that the temperature of generator 82 rises because. of blocking of the absorption liquid in the riser tubes therein, steam will flow through vent 88 into the common vent 82 and then pass into the atmosphere. Flow of steam through vent 82 from generator 82 may also occur because of rise in temperature of the generator resulting. from cessation of cooling water supply'to the absorber 48 and condenser 28.

effected by the heater I8, there may be loss of air circulation in duct 28 due to the operating failure of the blower 2 I Undenthese conditions loss of load on the heater I8 will cause flow of steam through vent 8| into the common vent 82 to effect heating of bulb 88, so that switch 84 will a,ae1,427

' The expansible fluid thermostat contains a suit- 7 During the heating periods when heating is being be openedto cut off the gas supply to the burners 58 and 58 and shut down the air conditioning system, as explained above. The switch 88 is also caused to open and shut off able volatile fluid the pressure of which decreases with fall of temperature. When the cooling element I1 falls below a predetermined low temperature the pressure of the volatile fluid decreases sufiiciently to cause normally closed switch 88 to open. This may occur, for example, when the blower 2| becomes inoperative during a cooling period and air ceases flowing over the surfaces of cooling element vI'I. When switch 88 .opens the refrigeration apparatus and auxiliary equipment associated therewith are shut down, as will be described presently.

Dascare'rron or Tnaauos'rs'r Corrraor. TC

In the above described air conditioning system in which heating, cooling, and ventilating are effected. it will now be understood that all of the auxiliary equipment, including the control and safety devices, are electrically operated or actuated. Referring now more particularly to Figs. 1, 2 and 4, the control for the air conditioning system comprises a thermostat control or device TC provided with a heating switch H, a ventilating switch V and a cooling switch R. Within the thermostat control TC are disposed switches S1 and S: which are caused to operate with rise and fall of temperature. As shown in Fig. 12, the thermostat control TC is located in the enclosure so that it is capable of effecting control responsive to a temperature condition affected by the air in the enclosure.

The switches H, V, R, Si and S: are connected in severalelectrical circuits located within the plated, depending upon thepositions of switches supply of gas to burners 58 and 88 in the event there is failure of pump 'I'I to return condensate from vessel 15 through conduit 18 to the boiler 81. Thus, when the pump 11 fails to return to the boiler the condensate collecting in vessel 18 during a cooling period, the liquid-level rises to a predetermined level and then overflows through a conduit 88 into a well 81 from which it flows to waste.

SI. and 8:, so that the devices connected to the terminals on. panel P with which these completed circuits are associated will'be energized to render In the well an is disposed a thermal bulb as which is connected in capillary tube 88 and forms .with thermal bulb 88 a part of the same expansible fluid'thermostat associated with switch 04.

Warmcondensate normally does not enter well 81 through overflow conduit 88, so that thermal bulb 88 will be ineffective to cause opening of switch 84- In the event thatthe'rmal bulb 88 becomes heated due to warm condensate overflow- 7 ing into well 81. because of failure-of pump 11, the

volatile fluid in the expansible fluid thermostat becomes sufliciently heated to cause opening-of switch 88, so that valves 81 and 88 will close to fluidthermostat andis connected by a capillary the air conditioning system operative to efiect either heating,-cooling, or simply ventilating.

Referring now more particularly to Figs. 1 to 9 inclusive, the thermostat control TC comprises a casing I88 mounted on back plate I8I which is adapted to be fastened on a wall in any suitable manner. To the top part of plate IN is secured an angle member I82, as shown in Figs. 2 and 5, having'the horizontal part thereof serving .as a support for the heating switch H, ventilating switch V, and cooling switch R. Each of the switches H, V, and R is enclosed in a casing I88 and provided with a. snap acting operating lever ormember I88 which extends through the top of the casing I 88.- The switches H and R are of the double-pole, double-throw type. and the ,switch V isof the single pole, double-throw type,

- as diagrammatically illustrated in Fig. 10, with these switches being connected to panel P in a manner to be described presently.

As best shown in Figs. 2, 5 and 6, a U-shaped main bracket I 881s located .within the casing I88 having the horizontal arms thereof secured at their rear ends by screws I88 to the back plate "I. A vertical plate I81, which will be referred to as i swinging or hinged door, is Journaled at I88 a to the top and bottom horizontal arms of main bracket I05. Tongues I09 are secured at one edge by screws' I I to the hinged door I01, as;

shown in Fig. 5. At a region near the hinge side of the hinged door'I01, the latter is formed with threaded openings to receive set screws I II which are positioned to bear'against the free ends of tongues I09, that is, the ends opposite to the end secured at IIO to the hinged door I01.

Referring more particularly 'to'Figs. and 6, the hinged door' I01 is biased toward the front of the casing I00 by coil springs II2 each having cne end secured to the front'vertical part of main bracket I05 and the other end secured to the edge of the hinged door I01 to which the tongues I09 aresecured. In the path of'movementof the hinged door I01 are disposed the pins or plungers II3 of switches 81 and S: which are mounted by screws II to. the vertical part of main bracket I05, as best showndniigs. 2, 4,

and 6. As diagrammatically illustrated in Fig. 10, the switches S1 and S2 are spring biased to a.

. first position to complete one electric circuit and are movable to another position to complete an- .other. electric circuit when pins II3 are moved toward thejront vertical part of main bracket I05.

The switches S1 and Si are completely enclosed and of the well-known-micro-switch type,

as illustrated in Figs-'1 and 8. The switches S1 and S2 include a movable element "5 which is fastened at II6 toone switch terminal. The eletionship with other parts of the thermostat control'TC.

An expansible fluid thermostat, which 0138! tivity, such as Bakelite, for example, and is p ovided with a recess I21 in the extreme lower part and openings I in the front and side walls thereof. The thermal bulb I is located in the recess I21 and extends from the front part of the block I23'toward the rear part. thereof onpositethe side openings I20, so that air circulating in the enclosure readily contacts and flows over the exterior surfaces of the thermalbulh I25. The rear part of the bulb I25 is'held in position by a lock plate I29Falso formed of a material having poor thermal conductivity, which is fastened by screws I30 to the bottomof the block I26.

The thermalbulb- I25 is connected by a capillary tube I30 to a pair ofexpansible andcon ment I I5 is provided with outer arms II1 which 1 are arranged to' spring-bias the element II5 to the position shown in Fig. 8, so that the element I I5 contacts an L-shaped stationary element IIO which is fastened at H3 to a second switch-ter-'- movement ofpin I I3 toward the left in Fig. 3, element H5 is caused to move and contact another .L-shaped element I2I which is inverted from the L-shaped element H0 and sfastened to a third switch terminal I22.

As best shown in Figs. 2 and '3, movement of "the pins us toward. the left is effected by movement of the hinged door I01 toward the front vertical part of main bracketl05. When the hinged door I01 moves toward the'rear of thermostat control TO, the pins II3 also move toward the right since the elements II5 of switches Si and S: are spring-biased to moveto the rear minal. The pin II3 forms part 1 a disc I20 which bears against element II5 whereby, with tractible elements I3I and I32, as best shown in Fig. 2. Referring more particularly to Figs. 2 and 5, the capillary tube I30 passes \through an opening in the rear of block I26 and also through a slot in the bottom horizontal arm of main bracket I05.- .The upper end of capillary tube I30 is spirallywound about ahollow hub member I33 having fa passage to which the extreme upper end of the capillary tubeis secured. As shown most clearly in Figs. '2 and 6, the hub member I33 is secured by screws I34 to the hinged door I01. By clamping the capillary tube I30 at 00 to thelower part of main bracket I05, as shown in Fi 2, movements of the thermal bulb I25 and the bottom part of capillary tube I30 will not be transmitted to the top spiral part of the capillary tube.

' 'Theelements I3I and l32 arein the form of expansible bellows or hollow diaphragms with one face of rear bellows I 30 secured toihub mem of a solid disc or diaphragm. The expansible position shownin Fig. 8 ,and also diagram- .matically illustrated in Fig. 10. As just pointed out; the fastenings 'at l I6, I I9 and I22 of switches si an'd'. Sr constitute terminals which are reoessed to receive the securing screws ill. As

shown most clearlyin Fig. 4 the screws Ill also serve to'fasten conductors2I'L-2I8, 250, 25L 23I 1 'and- 202 in place to connect the switches S1 and Si in the several electric circuits with which they are associated, as will be pointed out presently. In order that the's'ecuring screws l I4 jare-eifectively insulated from one another, the openings through which they pass in the vertical part of main bracket I05 are considerably larger than v the screws. As best shown in Figs. 2 and 4, the

. screws 1 II and switches Si and S: are properly located'in position by a plate I23 which is fast 'tened byscrewsIfl to the front vertical part' of main bracket I05. The positioningplate I23 is formed of insulating material and provided with openings whichare approximately the size 'of screws III, whereby the latter are positioned rangedto contact and engage the center, region ber I33 and the other face thereof secured to a second hollow-hub member I35. One face of the front bellows I32 is secured to the hub member I35 and the other face thereof is in the form bellows I3 I and I32 and the passages in hub members' I33 and I35 form a completely enclosed space which is in communication with the upper end of capillary tube-I30. The expansible'bellows I3 I and I32, capillarytube I30 and thermal bulb I25 constitute an expansible fluid thermostat which is filled with a suitable volatile fluidhave 'ing an. increasingly higher pressure with rise of temperature which causes swelling of the bellows and adecreasingly lower pressure with fall of a temperature to allow contraction of the bellows.

To'the peripheral edge portionof bellows I32 is 'fflxed one end of aleaf sprin I36, the other end of. which is provided with'a'depression arof. thebellows. 1 The depression in leaf spring I36 receives a pointed end of a pin I31, theother pointed .end of which .flts' into a recess in a set screw I38. The endsrof pin I31 are formed with-more or less smooth rounded points rather than sharp points.- The set screw I38 threadediy engages an adiu'stment put I 39 which in turn to hold switches 81 82in their desired rela- '15 I;hreaded1y engages a bushing I40 secured men. I

opening in the front vertical part of main bracket I05. I A circular dial plate I provided with a dial marked with temperatureindicia is fixed to the window I44 in casing I00. By turning the serrated peripheral edge portion I42 of dial I4I, therefore, the dial can be turned so that the desired temperature reading will be opposite the notch in 5 window I44. Inorder to insure that dial plate I will remain at the position to which it is adjusted-a coil sprin I45 is interposed between the rear face of the dial and the front vertical part of "main bracket I05. The tension of-spring I05 is such that dial plate I4I can readily be turned and at the same time sufhinged door I01, and even'with sidewise movement of. the bellows resulting from the Slight angular movement of hinged door I01, the needle I31 can freely deviate to a cocked position from a straight-line position. The fact that the needle I3I- can move freely, together with the provision of making the ends thereof tapered, insures that the same sensitivity is obtained at all times irre spective of the position of the needle with respect to the bellows I32. If the ends of needle I31 are too sharply pointed, objectionable wear results. For this reason the tapered ends are slightly rounded and lapped in to insure permanent calibration.

The leaf spring I35 is provided to prevent the needle I31 from dropping out of place in the event that the bellows I3I and I32 contract considerably, as when the thermostat control TC is flcient friction is provided to hold the dial in any position to which it is moved.

Within and at the rear of casing I00 is provided a heating element I46 which is connected to termiDBISTI and T: on panel P, as shown in Fig.

10. The heating element I46 .is provided to improve the responsiveness of the expansible fluid thermostat, as will be described hereinafter.

' The parts of the'thermostat control TC are interrelated in such a manner that dependable and accurate control of air temperature is effected. While considerable power is produced by the swelling of bellows I3I and I32, the hinged door I01 is arranged in such a manner that the microswitches S1 and S2 are not directly acted upon by the bellows. In control TC the greatest swelling needle I31 to hold the latter in position.

shipped during cold weather. The leaf spring I35 is relatively weak with the end thereof adjacent the center of bellows I32 normally hearing against the latter. With considerable contraction of bellows I 3| and I32, the leaf spring I36 exerts suflicient force against one end of In such case there is slight movement of spring causes the hinged door I01 to move from and not toward the switches 81 and S2, whereas in controlsemploying expansible bellows it is usual. ly the practice for the swelling of such bellows to cause force to be imposed upon the switch mechanism. The highest forceis imparted to the switches Si and S: when the hinged door I01 movestoward the front vertical-part of main bracket I05 and the tongues I00 engage and cause'movement of the switch pins or 'plungers H3. This movement of thehinged doorI0l is .eflected by the pulling action of coil springs 2- -can,be mounted thereon at one end and the set screws III employed to adjust the position of the free ends of the tongues to determine .the particular moment when the tongues contact and engage the pins H3. This insures accurate setmcvement oi the hinged door I01, and is a declded improvement over an arrangement where set screws alone are employed, because set screws.

t nd to wobble and move in the threads in which they are engaged."

In order to reduce to a minimum the friction produced at the operative connectionv of bellows I32 and set screw I38 the tapered-ended needle or pin I3! is employed. The needle I31 is offset of the,

with respect to the pivotal connection I08 135 with respect to bellows I32, and when the bellows I3I and I32 again expandsufflciently to assume a position in the normal temperature range encountered during operation of the air conditioning system, the depressed portion of spring I36 is again pressed against the forward diaphragm of the bellows I32.

The main bracket I05 is made exceptionally rigid and strong because allof the working parts of the thermostat control TC are mounted on this bracket. In fastening the main bracket I05 to the back plate I0I only two fastening screws I05 are employed, as best shown in Fig. 2. Further, the contact surfacesbetween main bracket I05 and backplate IIlI are small by forming lips 91 at the rear ends or the top and bottom horizontal arms, as shown in Fig. 6, which are considerably narrower than the width of bracket I05. With this arrangement bending or warpingof bracket I05 is avoided as much as possible in the event backplate IOI -is bent or strained when mounted in position, so that the likelihood of partsgetting out of adjustment is minimized.

I Etrzornrcllr. SYSTEM CONNECTING Trrnamosrs'r Con- TROL TC AND Ensc'rarcar. APPARATUS Assocra'rrm wrrn Ara Connrrromc Srsrnr The terminal panel P is fixed to the rear side of back plate IOI, as shown in Figs. 2 and 9. The manually operable switches H, V and R at the top of thermostat control T6, and switches S1 til) .' ting of the instant when it is desired to actuate.

the switches S1 and S2 after a' definite amount of and S2, which are operable in accordance with rise and fall of air temperature in the enclosure I4,- are connected in several electric circuits to different terminals on the panel P. In order to simplify as much as possible the. illustrations of the structural features in Figs. .1 to 8 inclusive,

the electrical connections of the several switches to the terminals on panel P have been omitted in these figures. The connections to panel P of the several switches described'above are, however, diagrammatically illustrated in Fig. 10 to facilitate an understanding of the control circuits. The circuits shown in Fig. 10 and their association with the circuits illustrated in Fi 11 will now be explained in describing the operation of theair conditioning system.

When it is desiredto operate theair conditioning system describedabove, main switch 200 in Fig. 11 is closed, so that the primary winding 20I of transformer 202 will be connected to a 7 suitable alternating current source of electrical energy. The circuit completed for energizing the transformer 202 includes conductors 203 and 204 which are connected-tothe source of electrical supply and in which is provided the switch 200, and conductors 205 and 205 which'a're connected to opposite terminals of the primary winding 20 I. The transformer 202 is a step-down transformer with one terminal of the low voltage secondary winding 20'I connected by conductor 200 to terminal I: on panel P, and the other terminal thereof connected by conductors 205 and 2I0 to terminal T]. on the panel. Hence, when main switch 200 is closed, terminals T1 and T: on panel P are energized and anv circuit completed across' these terminals will be energized.

' I Heating Let us assume now that main switch zuu is closed and that it is desired to operate the air conditioning system in Fig. 12 togieat air in the -in Fig. 1' is then'snapped'to its forward position to cause operation of the air conditioning system to render the latter operable to eflect heating. Referring more particularly to Fig. 10, movement "'1 ductor 2I2, left-hand element 2l3 of. switch R,

' conductor 2, connecting link 2I5 on'panel P,

conductor 2I5, left-hand element 2 of switch ductor '2IB, right-hand element 2II of switch H,

of lever I04 of the heating switch'H causes the movable elements 2 thereof to move from the "oi!" position to. the "on position. When the temperature of the air issufliciently high, that- 'is, at 70 F. (the assumed temperature at whichof air is' effected by the air conditioning system. When the airtemperature starts to fall below the desired temperature of 70 F., the pressure of the volatile fluid in the expansible fluid thermostat decreases so that the bellows I lI-and I02 contract. With contraction of bellows (Ill and I32 the coil springs II2 are efiective to pull the hinged door I01, toward the front vertical part of main bracket I05. As shown in ,Fig. 10, the

forward movement of the hinged door I01 causes movement of the pins 3 of switches CS1 and 8:. The switche s Si and-S2 are so located and arranged thatthe movable element II5 of the bot-" tom switch, Si is actuatedflrst with movement of the hinged door I01 toward the front'vertical part of bracket I05, and,'with continued movement of the hinged door in the same irection, I

Qtly/fiidvable element II 5 of the top switch Si ,is thereafter actuated- When the movable element switch Seis actuated, this element moveswith' a .snapaction from the position shown in solid' lines to that'shown in dotted'lines'inFlg. 10-.

pleted across the terminal -T1 and T: on panel P to'render the air. conditioning. system operable to heat air 'in the enclosure I4.

m of'thejbottom conductor 2I9, element 220 of switch V and con-' ductor 22I to the terminal V on panel P. Referring now to' 1'*ig.- 11 the completed first circuit-further includes a conductor 222 which is connected to terminal V; coil of blower nrotor relay 2 28, conductors 224 and 225, normally closed switches 84 and 93 and conductor 220 to terminal Ta on-panel P.

Since-terminal Ti and T2 are energized when main switch 200 is closed, as pointed out above, and the circuit just described is completed across these terminals, it will be evident that the coil of blower motor relay 223 is energized to close this relay." Energization and closing of relay 223 comsource of electrical supply includes conductors 203 and 221, the 'movableelement of relay 223 and conductor228 which is connected to oneterminal of blower motor 28. The opposite terminal of blower motor 28 is connected by conductors 220 and 204 back to the source of electrical supp y. In the circuit described above which is completed from the terminal T1 on panel P to the terminal V, the .cireuit was followed from the element H5 of the bottom switch S2 in Fig. 10 through conductor 2 I0 to the right-hand element 2 of switch H. From the terminal Ti-a second circuit is completed which includes a portion of the first circuit up to and including the con ductor 2 It From conductor 2I8 the second circuit also includes conductor 820 which isconnected to terminal So on panel-P. Referring now. to Fig, 11, the second circuit further includes conductor 23l which is connected to terminal S2, solenoid ope'rated gas valve 58, conductor 232, the movable element of low-water cutout relay l9, con-ductor 225, normally closed switches 84' and vat, and conductor :26 to terminal T: on panel P.

The second circuit just described includes the low-water cutoutrelay I9 which, as pointed out above in describing the air conditioning system- When the water in the boiler 31. is at or above a predetermined level, the. circuit for relay-19 is completed across the terminals T1 and I: on panel,

P. This circuit from terminal Ti includes conductors 2I0 and 233 to one terminal of the relay 10, the opposite terminal thereof being connected through conductor 225; normallyclosed switches 84 and 93 and conductor 220to' theterminal T2.

With the coil of relay'19 beingenergized, the movable element of-this relay will beactuated to its closed position immediately upon closing of the main switch 200. With relay I9 closed,

it will be apparent that the second] circuit described 'willbe completed across the terminals T1 andTz on panel P to actuate and open the.

' When this occurs a number e: circuits are com-" I The above described movement of element Ill of"-swit ch Sate the dotted line position in Fig. 10

electrically-Operated solenoid valve 50;

With movement of the element II5 of bottom switch 8: to the dotted line position shown in Fig-10, a third'circuit is completed which also.

includes a portion of the first described-circuit .up to and including conductor 2I8. From concompletes a first circuit from Tithrough con-' '10 hand element 2 ofswitch H, conductor 234, the

right-hand element/2 ll of switchR and conductor 285 which is connected to terminal H on panel P. Referring now to Fig. 11, the third circuitfurther includes a conductor 288 which is connected to terminal H, the two-position electric motor 6|, conductor 228, normally closed switches 84 and '98 and conductor 228 which is connected to terminal T2. pleting a circuit for the two-position electric motor 8|, the third circuit also completes a cir- 22 and opening of dampers 24.

.cuit for the electrically-operated solenoid valve 2! which is connected to conductors 288 and 228 below the predetermined level determined by the In addition to com- As shown in Fig.-12, the opening 01 gas valve 88 allows gas to be supplied through conduits 88 and 88 to the burner 54. The gas discharged from the burner 84 is ignited by the pilot flame. formed at the end of tubing 88, so that boiler 31 is heated.

At the same time that heat is being supplied the steam valve 88 so that all or the steam produced in the boiler will now through conduit 88 to the heater l8. Simultaneously with the actuation 01' steam valve 88 the right-hand end of lever 18, which is operatively connected to the I two-position electric motor", moves downward to the position shown in Fig. l2..to increase the tension of spring 88 of the gas pressure regulator 81. By increasing the tension of spring 88 gas is" supplied to burner 88 at a higher constant pressure than during the periods when the air conditioning system is operating to effect cooling of .air, as explained above. The above-described actuation of steam valve by two-position 1 of dampers electric motor. 8| also causes closing to the boiler 81 toproduce steam, the two-position electric motor 6| becomes operative to actuate location of the low-water cutout relay is, this relay will open to break the circuit in which the solenoid-operated gas valve 58 is connected, as shown in Fig. 11. However, when gas valve 58 is closeddue to deenergization of the low-water cutout relay 19; the other circuits remain completed so that the entire system is not completely shut down.

When the air temperature continues to fall below the desired temperature of 70 F., even when the single burner 58 is operating as a result of the movement of element N of the bottom switch S2 to the dotted line position shown in Fig. 10, the continued movement of the hinged door I81 toward the front vertical part of main bracketlllli imparts sufllcient movement to the top pin 8 in Figto move the element N5 of switch S1 with a snap action from the position shownin solid lines to that shown in dotted lines. When'this occurs the circuits already completed as a result of the prior movement or element ll! of the bottom switch S2 remain intact to cause heating of air in the enclosure. In addition, a circuit is completed from the terminal Tr which includes a portion of the first-described circuit up to and including the conductor 2H. From conductor 2n the .additional circuit includes a conductor 250, element 5 of top switch S1, and

, conductors l and 252 which are connected to The energizationvoi blower motor 28 renders the blower 2 l operative to cause circulation of air past the heater l8, the air being withdrawn from the enclosure I through ductsl8 and 28 and the heated air being returned through duct 22 to the enclosure. The opening of solenoid-operated water valve 21 permits water to be supplied to V no e 28 so that humidification of air-can be eflec The condensate formed in heater l8 returns through conduit. 14 to the boiler 81 by gravity.

In the event through vent 8| to the common vent 82, due to operating failure of the blower 2!, forexample,

' the thermal bulb 88 becomes heated and the ex-- position motor 8 l pansible fluid-thermostat or; which this bulb forms a'part causes switch, 84 to open. As shown in Fig. 11, opening of switch 88 opens all of the clrcults connected to the terminal T2 onpanel P,

. normal operation of the system described above isresumed to effect heating of air in the en- 8 closure M. The switch 88 may be of the manual re-set type so that manual closing of the switch.

that steam flows 'n-bni heater l9 terminal $1 on panel P. Referring now to Fig.

11, the additional circuit further includes a conductor258, solenoid-operated gas valve 51 and conductor 284 which is connected to the terminal T2 in thesame manner as solenoid-operated gas valve 88. L

Hence, when there is such fall or temperature that the exp'ansible bellows l3l and 182 contract sufliciently to allow thehinged door IM to cause the element H5 of the top switch S1 to move tc its dotted-line position after similarly actuating the bottom switch S2, all or the devices energized as a result of the actuation of the bottom switch S: remain energized and a single new circuit i:

with which thebellows are associated.

to the burner 58 to increase the rate at which heat is supplied to the boiler 81, so that an increased amo'untof heating will be eflected by the heater l8.

Conversely, when the air temperature in enclosure ll rises, the bellows I 3| and H32 expand and swell due to increase in pressure of the volatile fluid within the expanslble fluid thermostai The swelling and expanding of bellows lSl and 93: produces a force which is exerted against the hinged ,door lli'l to cause the latter to move rearwardly against the action of coil springs M2 When the hinged door I81 has moved rearwardl: 'sumciently; the element 5 of the top switch 81 moves back to the solid line position in Fig. 10 This movement of element 5 toward the righi is inherent in switch S1 because, as explained above, the elements I I 5 of the switches S1 anc S: are spring-biased to move rearward when the' hinged door I8! is ln'such a position that it wil not restrain or limit rearward movement of th( pins H3.

With movement of'the element N5 of to SWltChBi toward the right in Fig. 10,'the circuii from terminals T1 to Sr on panel P is broke:

to its forward position to cause operation of the. air conditioning system so as to effect air coolwherefore the circuit for the solenoid-operated. v gas valve 31 is opened to cause the latter to close":

The closing of gas valve 51 shuts oil flow of gas to When the air temperature in the enclosure I4 rises to the desired temperature at which the dial mounted on plate MI is set, suflicient expansion and swelling of bellows BI and I32 results to cause the hinged door H" to move rearwardly such a distance that the element of the bottom switch S2 snaps rearwardly to the solid line.

position in Fig. 10. With movement of element H5 of the bottom switch S2 to the right in Fig.

. 10'. all of the circuits previously completed from terminals T1 to V. H. and S: on panel P are broken, so that. all of the devices'connected to these terminals are deenerg'ized to shut down the system. When the temperature of air in the enclosure 54 again .falls below the desired temperature of, say, 70 F., switch S2 is again actuated to cause the air conditioning system to operate to effect heating of air flowing past heater l3.

Ventilating Let us assume that main control switch 200 in Fig. 11 is closed so that a circuit formed across the terminals T1 and T2 on panel P will be completed to cause energization of any device connected therein. Let us further assume that simply ventilating of enclosure I4 is desired, with-. out heating or cooling of" air delivered theretothrough duct 22. In suchcase the middle or center lever I! at the top of thermostat control TC in Fig. l is snapped to its forward position for operating ventilating switch V.

Referring more particularly to Fig. 10, movement of lever I04 of switch V causes the movable element 22!! thereof to move from the "o position to the "on position to complete a circuit across the terminals Ti and T2 for the blower motor relay 223 in Fig. 11. This circuit includes conductor 2 l2 which is connected to the terminal T1, conductor 251, element 220 of switch V, and conductor-'22! which is connected to the terminal V on panel P. Referring now to Fig. 11, the circuit being described includes the conductor 222 which is also connected to terminal V, coil of blower motor relay 223, conductors 224 and 225,

i normally closed'switches 84 and 93 and conductor 226 to terminal T: on panel P.' With energize tion of the blower motor relay 223, the movable element thereof closes'to complete the circuit for the blower motor 28 across conductors 203 and 204,- as previously explained above under the heading Heating. By completing the circuit for blower motor 23, the blower 2| is operated to withdraw air from the enclosure I 4 through duct l5 and return air through duct 22 back to the enclosure H, thereby effecting ventilation of the enclosure ll. This feature is desirable during periods when neither heating nor cooling of air are necessary and yet the amount of comfort that occupants desire isimproved considerably 'ature-of the air is sufllciently low,

are in the dotted line positions shown in Fig. '10

and none of the circuits of the devices shown in Fig. 11 is completed, so that no cooling 01' air is eifected by the air conditioning system. I

When the air temperature starts to rise above, say F., for example, the pressure of the volatile fluid in the expansible' fluid thermostat increases to cause the bellows i3i and 832 to swell and expand. With swelling of bellows i3! and I32, the hinged door I0! is forced rearwardly from the front 1 vertical part of main bracket 165 against the action of coil springs H2. As shown in Fig. 10, the rearward movement of the hinged door permits movement of the pins H3 of switches S1 and S2 toward the right. With move-, ment of the hinged door I01 toward the right in Fig. 10, the movable element H5 of the top switch S1 first moves with a snap action to its solid line position, and, with continued movement of the hinged door in the same direction, the movable element '5 of the bottom switch S2 thereafter moves with a snap action to its solid line position.

When the movable element N5 of top switch S1 moves with a snap action from the position shown in dotted lines to that shown in solid lines, a number of circuits are completed across the terminals T1 and T2 on panel P to render the air conditioning system operable to cool air in the enclosure H. The above-described movement of element H5 of top switch S1 to the solid line position in Fig. 10 completes a first circuit from T1 through conductors H2 and 260, lefthand element 2| I of switch H, conductor 2 I6, connecting link 2l5 on panel P, conductor 2, lefthand element 2| 3 of switch R (which is-now assumed to be in the on position), conductors.

conductor 219, element 220 of switch V and conductor 22! to the terminal V on panel P. Referring now to Fig. 11, the first circuit also includes conductor 222 which is connected to terminal V, coil of blower motor relay 223, conductors 222 and 225, normally closed switches 84 and 93 and conductor 226 to terminal T2 on panel P. With completion of the circuit just described across the terminals T1 and T2, the 'coil of blower motor relay 223 is energized to close the movable element associated therewith to complete a circuit for the blower motor 23 across conductors 203 and 204. This circuit has previously been described above under the headings Heating and Ventilatingand will not be repeated here.

when air circulation and .air cleaningare ef.-

fectedfi" Cooling J Let us assume now that main switch 200' in Fig. 11 is 'closedand that it is desired to operate the air conditioning systemin Fig. 1 12 to effect cooling of air in the enclosure I I. The lever Hi4 of the cooling switch-R at the extreme right-hand .side of thermostat control TCin Fig. 1 is snapped In the first circuit described above, which is completed from the terminal T1 to the terminal V, the circuit was followed. from. the element I I5 of the top switch S1 in Fig. 10 through conductor .2'5l to the right-hand element 2 of switch H. From the terminal T1 a second circuit is completed which includes a portion of the first circuit up to and including the conductor 25 i. From conductor 25l the secondcircuit also includes conductor 252 which is connected to terminal $1 on panel P. Referring now to Fig. 11, the second circuit further includes conductor 253 which is connected to terminal S1, solenoid-operated gas valve 51, conductors 2-54 and 232, the movable element of low water cut-out relay [9, conductor 225, normally closed switches 84, 93, and conductor 226 to terminal T2 on panel P. As .already pointed out above under the heading Heating, the low water cutout relay 19 is immediately energized when main switch 200 is closed as long as the water in the boiler 31 is at a predetermined level. described, the energization of solenoid-operated gas valve 51 is effected to cause this valve to open.

With movement of the element H5 of top switch S1 to the solid line position shown in Fig. 10, a third circuit is completed which also includes a portion of the first described circuit up to and including conductor 25! and right-hand element 2!! of switch H. From the element 2H of switch H the third circuit includes conductor 234, the right-hand element 2 l3 of switch R, and conductor 263 which is connected to terminal C on panel P. Referring now to Fig. 11, the third circuit further includes a conductor 264 which is connected to terminal C, the two-position electric motor 6| conductor 225,'normally closed switches 84 and 33 and conductor 226 which is connected to terminal T2. The circuit completed for the motor 6| through terminal C causes the motor to turn to a position opposite to the position taken when a circuit is completed for this motor through terminal H and conductor 236.

In addition to completing a circuit for the twoposition electric motor 6| the third circuit also completes a circuit for the spray tower relay 265 which is connected by conductors 266 and 261 to conductors 264 and 225 in parallel with the twoposition electric motor 6|.

With completion of the above described third circuit resulting in energization of the coil of relay 265, the movable elements thereof close to complete circuits for the spray tower motors 50 and 52 and the condensate pump motor 18. The circuits for the spray tower motors '50 and 52 from the source of electrical supply include conductors 203, 240 and 268, the movable elements of relay 265 and conductors 263 and 210 to the terminals of the spray tower motors 50 and 52..

From the opposite terminals of motors 56 and 52 the circuits include conductors 229 and 204 which areconnected to the source of electrical supply. In addition, the energization of relay 265 completes a circuit from the source of supply through conductors 233 and 240, one of the m ovable elements of the relay 265 and conductor 243 to one terminal of the condensate pump motor I8. The circuit from the opposite terminal of motor 18 includes conductors 244, 223 and 204 which are connected to the source of electrical sunp y- When the element H5 of top switch S1 moves to its solid line-position in Fig. 10, therefore, the three above-described circuits, which are completed through terminals V, 81 and C on panel In the second circuit just i tion electric motor becomes operative to actuate the steam valve 60 so that all of the steam produced in the boiler will flow through conduit 36 to generator 32 of the refrigeration apparatus. By supplying steam to generator 3 2, the refrigeration apparatus operates in the manner described above so that cooling element I1 becomes efiective to produce a refrigerating or cooling efiect. Simultaneously with the actuation of steam valve 50 the lever 10, which is operatively connected to the two-position motor 6|, movesfrom the position shown clear of pin 69 in Fig. 12. With the right hand end of lever 10 in its raised position gas is supplied to burner 53 at a constant pressure dependent upon the tension of spring 68. Under these conditions gas is delivered at a lower constant pressure than during the periods when the air conditioning system is operating to efiect heating of air, as explained above. The abovedescribed actuation of steam valve 60 by the motor 6| also causes closing of dampers 24 and opener 23 and condenser 49 of the refrigeration apparatus. The condensate formed in :generator 32 flows through conduit 13 to the vessel 15 and is returned therefrom to the boiler 31 by pump 11 which is actuated by the condensate pump motor 18.

In the event that steam flows from generator 32 through vent 80 to the common vent 82 for any ofthe reasons previously given, the thermal v bulb 83 becomes heated to cause switch 84 to open all of the circuits connected to the terminal T2 on panel P, in the same manner that all of the circuits are broken during a heating period, as explained above.- Likewise, if there is operating failure of the condensate pump 11 or the water in boiler 41. falls below the normal predetermined level determined by the location of the low water cut out relay 19, the switch 84 will open if the former occurs and the circuit for the solenoidoperated gas valve 51 will be broken if the latter occurs. In the event that cooling element l1 falls below a predetermined low temperature, the

thermal bulb 9| becomes sufllciently cool to cause switch 93 to open all'of the circuits connected to the terminal T2 on panel P, so that all of the electrical circuits are broken to shut down the air conditioning system.

When the air temperature continues to rise above the desired temperature, even when the single burner 53 is operating as a result of the movement of element H5 of the top switch S1 to the solid line position shown in Fig. 10, the continued movement of the hinged door I01 rearwardly from the front vertical part of main bracket I05 permits the bottom pin H3 to move to'the right to allow the element H5 of the bottom switch S2 to move with a snap action from the position shown in dotted lines to that shown in solid lines. When this occurs the circuits already completed as a result of the prior movement of element H5 of the top switch S1 remain intact to effect cooling of air in the enclosure. In addition, a circuit is completed from the terminal Tr which includes a portion of the first described circuit up to. and including-the conductor 26!. From conductor 25| the additional circuit includes element iii of the bottom switch Sz'and conductors H8 and 231: which are connected to terminal S: on panel P. Referring now to Fig. 11, the additional circuit further includes conductor 23! which is connected to the terminal 8:, and solenoid-operated gas valve 58 which is connected to the terminal T: in the same man ner as solenoid-operated gas valve 51.

Hence, when there is such rise of temperature that the expansible bellows i3! and I82 swell sumciently to cause the hinged door I01 to permit the element N of the bottom switch S2 to move to its solid line position after previously permitting the element H5 of the top. switch S1 to move toward the right, all of the devices energizedas a result of the actuation of the top switch S1 remain energized and a single new circuit is completed to open solenoid-operated gas valve 58. With opening of gas valve 58 gas is also supplied to burner 54 to increase the rate at which heat is supplied to the boiler 31 so that an increased amount'of cooling will be effected by the cooling element I'I.

Conversely, when the air temperature in enclosure H falls, the bellows HI and I32 contract due to decrease in pressure of the volatile fluid within the expansible fluid thermostat with which the'bellows are associated. With contraction of bellows [3| and I32 the coil springs H2 are effective to pull the hinged door Ill! toward the front vertical part of main bracket "15. When the hinged door I01 has moved forward sufllciently the pin N3 of the bottom switch S2 causes .the element H5 associated therewith to move with a snap action to the dotted line position in Fig. 10.

With movement of the element N5 of bottom switch S2 toward the left in Fig. 10, the circuit from terminals T1 tO-Sz on panel P is broken, so that the circuit for the solenoid-operated gas valve 58 is opened to cause the latter to close. The closing of gas valve it shuts ofl flow or gas to burner 54 to reduce the heat supply to the boiler 8,! and hence decrease the amount of steam produced and delivered to generator 32. with a reduction in the quantity of steam supplied to generator 32- the cooling efiect produced by cooling element I1 is likewise reduced.

When the air temperature in the enclosure ll falls to the desired temperature at which the dial mounted on plate I is set, suincient contractionof bellows l3! and I32 results to cause the hinged door Hi! to move'forward such a distance that the element N5 of the .top switch S1 moves with a snap action to the dotted line position in Fig. 10.

is connected to terminal V. With the circuits completed from terminals T1 to V, S: and H, the devices connected to these terminals and also Ts will be energized to cause heating of air in the manner described above under the heading Heating.

When both the cooling and ventilatingswitches R and V are moved to the "on" positions the system becomes operative to effect cooling of air in the enclosure 14. T1 to S1 and C on panel P in such case are the same as the second and third circuits described above under the heading Cooling. The circuit from terminals Tl to V difiers from circuit previously described under the heading Heating, and is the same as that Just described when both switches H and V are moved to the on positions at the same time. With the circuits completed from terminal T1 to V, S1 and C, the devices connected to these terminals and T: will be energized to eflect cooling of air in the manner Y described under the heading Cooling."

When both the heating and cooling switches H and R are moved to the "on positions no circuits are completed from T1 to other terminals on the panel P. This is quite evident because the conductor 212, whichis'connected to terminal T1,

When the element H5 of the top switch 81 moves to the left'in Fig. 10 all of the circuits previously completed from terminals T1 to V, S1 and C on panel P are broken, so that all oithe devices connected to these terminals are deeneregized to cause the system to shut down. When the temperature of air in the enclosure I 4 again rises above the desired temperature, switch S1 is again actuated to'cause the air conditioning system to efl'ectcooling of air flowing past cooling element l'l. y Operation of electrical system when several control switches are on at-the same time When both the heating and ventilating switches H and-V are moved to the on? positions the air conditioning system becomes operable to heat cannot complete any circuit through the lefthand element 213 of switch R; and the conductor 260, which is connected through conductor 2l2 to the terminal T1, cannot complete any'circuit through the left-hand element 2 of switch H. Also, the conductor 261, which is connected through conductor 2l2 to the terminal Ti, cannot complete any circuit across the element 220 of the switch V. Since none of the circuits is completed from terminal T1 to another terminal-on the panel P when both switchesH and' R are moved to the on positions, none of the devices will be energized so that the system will be ineriective either to heat or cool the airin the enclosure M.

When all the switches H, V and R are moved to the on positions no circuits are completed from T1 across the movable elements 2! I and 213 of switches H and R, respectively, in the manner just described when both of these-switches are moved to the on" positions. However, when switch Vismoved to its 011" position at the same time as the switches H and R, a circuit is completed from terminal Tito V on panel P in the same manner described above when switches H and V are moved at the same time to their on" positions. Hence, when all three switches on thermostat control TC are moved to the "on positions, ventilating of enclosure will-be effected.

In view of the foregoing, it when switches H and V are in the on" positions at the saine time, ventilating or the enclosure I4 is constantly effected even when the air temperature rises suiilciently to render the system in eflective for heating air. Likewise, when switches R. and V are in the on positions at the same time, ventilation is effected even when the air temperature is sumciently low to cause the re- The circuits from terminal will be evident that frigeration apparatus to shut down. In most cases it is desirable to keep the ventilating switch V in the o position when heating is being effected, so thatthere will be intermittent operation of the blower 2I and to keep the switch V in the on position when cooling is being effected, so that there will be continuous operation of blower 2| to promote the best comfort conditions.

Electrical system modified for heating only When it is desired to employ thermostat control TC for heating only, with all of the circuit removal of connecting link 2I5 on panel P and the substitution therefor of connecting links 213 and 214, as indicated in dotted lines in Fig. 10. By providing link 213 a circuit is provided from terminals T1 to V during heating which is generallysimilar to that described above under the heading Heating and differs therefrom only in that a shunt or by-pass is provided around the left-hand element 2 I 3 of cooling switch R. Hence, irrespective of the position of switch R the circuit from T1 to V includes link 213 and conductor 2I6 to the left-hand element 2 of switch H. From this point the circuits'to terminals H, S2 and V are similar to the circuits described above under the. heading Heating, except for the following possible modification of the circuit to the terminal H which involves the connecting link 2".

The connecting link 214 is provided so that a circuit'will always be completed from terminals T1 to H when switch H is moved to it .on position, irrespective of position of the right-hand element 2I3 of switch R. When the switch R is in the position shown in Fig. 10, the circuit to terminal H is completed through conductor 234, the right-hand element 2I3 of switch R and conductor 235 which is connected to terminal H. When the switch R is moved to its on" position, the circuit from conductor 234 is then completed through the right-hand element 2I3 of switch R and conductor 263 which is connected to terminal 2 c. In order thatthe circuit will still be completed to terminal H even when the switch R isin the on position, the connecting link 2' is provided from terminal C to H. Hence, irrespective of the position of switch R in Fig. 10, when the switch H is in its on position and there is a demand for heat, a circuit will aways be completed to terminal I 32 are formed of beryllium-copper approximately .016 inch thick with the diaphragms being heat treated to maximum hardness after the peripheral edges thereof have been secured by silver solder. The bellows I3I and I32 formed of beryllium-copper together expand approximately .0016 inch per degree Fahrenheit to effect a snap-action movement of each micro-switch S1 and S2 employed in the control, amovement of only .00015 to .00035 inch being required with a. change in pressure of 1% to 2 ounces on the plungers or pins H3.

The expansible fluid thermostat of which the bellows being described form a part preferably has also-called limited charge of isobutane, that is. the charge of'volatile fluid is sufiicient to produce 'sa'turated vapor with a temperature as high as 95 R, which is safely above the upper limit of the thermostat adjustment of control TC. In such case the bellows I3I and I32 contain superheated vapor above 95 F., so that the pressure at extremely high temperatures frequently encountered during shipping and storage only increase: slowly according to the ideal gas law. By employing an expansible fluid thermostat havin only a limited charge, the pressure increase thaI occurs with rise of temperature above the normal working temperature range is limited, so that the diaphragms of the bellows can be formed from relatively thin material from which more useful movement can be obtained. It is desirable to employ a volatile fluid having a high vapor pressure, such asisobutane, for example, in ordei to reduce the effect of barometric changes Hence the expansible fluid thermostat including the bellows I3I and I32 should be sumcientls strong to withstand the pressures of volatile fluid: havingahigh vaporpressure.

The thickness of the diaphragnis forming thr bellows I3I and I32 and the size thereof should always be selected so that straining above the elastic limit is avoided under all the conditions encountered.

As explained above under the heading C'ooling the top switch S1 is moved first from the dotted line to the solid line position in Fig. 10 witl rise of air temperature, and thereafter the botton switch S2 is similarly moved with further rise 01 air temperature. The adjustments embodied ir control TC are made so that, when the temperature increases during a cooling period from the desired temperature and the hinged door I Ill i:

push'ed rearwardly due to expansion of the bellows I3I and I32, the top switch S1 is operatet first. In the control TC referred to above, thi:

, is accomplished by' first positioning the top tongue I09 by the set screw II associated therewith S( that the top switch S1 is operated when she hingec H so that the. devices connected thereto and also to terminal T: will be energized to render the system operative to heat air in the enclosure I4.

SENSITIVITY or THERMOSTAT Com'nor. TC

Under the heading Description of Thermostat control T appearing above, the structural features of the control have already been described.

The interrelation of the subsidiary andcomponent parts of the control TC is such that dependable is eflected. In such control the bellows I3I and door is moved from a position parallel to the from vertical part of main bracket I05 3, distance in 2 range varying from .00015 to .00035 inch. Thi:

operation of switch- S1 in the control being described requires a temperature rise of between 0; to 0.6 F. A slight movement of the hinged'dooi I0! is preferably allowed before the bottom switcl S: is actuated, such movement in one instance corresponding approximately to a temperaturl change of about 0.2" F. The bottom switch S2 11 the control referred to above is then operatec avgth a further temperature rise between 0.3 (K

In the two-step or two-stage control just described, therefore, the operation of both burner: 53 and 54 is effected with a temperature difieren tial of approximately or slightly greater than 1 F. Thetwo steps or stages of operation can, 0:

to cause the free end of the bottom tongue I08 to move toward the front vertical part of main bracket I05, the temperature change that occurs between. the operation of the to and bottom switches is increased.

The factors that determine the extent of temperature change that should occur between operating the system with the first step or one burner and with both steps-or two burners include the size of the space in which air is to be treated or conditioned,'the heat capacity of the building or dwelling,- and the time lag that occurs when the control equipment and associated devices are set into operation and also rendered inoperative.

In view of the foregoing, it will now be under-,- stood that the. thermostat control TC isextremely sensitive by virtue of the structure and interrelation of the component parts thereof and the fact'that a negligible amount of friction is produced during operation of the control.

- 'RESPONSIVENESS or THERMOS'IA'I CONTROL TC In addition to being extremely dependable and sensitive in operation the thermostat control TC embodies an expansible fluid thermostat which is so constructed and arranged that the control is exceptionally rapldin responding to change of air temperature.

For this reason the thermostat control TC is provided with an expansible fluid thermostat which comprises not only the expansible and contractible bellows I3I and I32, which is the usual practice in bellows type thermostatic controls heretofore provided, but also the capillary tube I30 and thermal bulb I25. In addition, the heater I 48 is provided to cause heating of air within the casingiilil so that the bellows I3I and I32 and larger part'of capillary tube I 30 will be disposed in an environment which is at a slightly higher temperature than the bulb I25 located in the recess I21 formed in the bottom part of the control.

' In any expansible fluid system the pressure therein always corresponds to the temperature of the coldest part, because the temperature attained by the coldest part determines the amount of volatil .fluid in liquid phase and in gas or vapor phase. When thetemperature of the cold- ,est part rises a greater amount of volatile fluid is in gas phase to cause the pressure in the system to increase; and conversely, when the temperature of the coldest part falls, some condensation occurs with a smaller amount of volatile system to reduce.

In order to insure will always be at a. lower temperature than other parts of the thermostat system, and hence serve 'as the only sensitive part of the system, the other parts thereof comprising. the capillary, tube I30 that the thermal bulb ms 'expansible fluid thermostat having as small an internal volume as practicable and at the same time of such proportion that adequate mechanical energy will be produced to cause operation of the thermostat control TC. 4 The thin-walled thermal bulb I25 at th bottom of the control TC is well exposed to the air so that the thermostat as a whole responds rapidly to changes in'air temperature. It is desirable to form the bulb I25 as small as practicably possible and with relatively thin walls, so that there is very little heat absorption by the metal with rise of air temperature and very little heat dissipation by the metal with fall of temperature. This is quite different from expansible fluid thermostats of the type heretofore provided which employ 'expansible and contractible bellows alone and are relatively sluggish in operation because of the relatively large amount of heat required to be taken up and given off bythe diaphragm metal forming. the bellows. 1

With the so-called limit charge of isobutane, for example, the sensitive bulb I25 only contains volatile liquid in the order ofa few hundredths 1 of a cubic inch at the lowest regulating temperavolatile fluid is now in gas phase within the thermostat' system, the internal pressure increases to cause mechanical movement of the control parts,

the bellows I3I and I32 acting with considerable power to effect movement of the hinged door IIl'I. Conversely, with fall of air temperature heat is the volatile fluid through 'densation of vapor. now in vapor phase the internal pressure within the thermostat system is reduced to cause or permit movement of the control parts.

fluid in gas phase to cause the pressure in the It should be understood that the heater I46 is continuously and constantly heating the inteso rior of casing in of the thermostat control TC. The heater I46 is immediately energized across terminals T1 and T2 on panel P when the main control switch 200 is closed, as best shown in Fig. 11. The heater M6 insures that the temperature 'within casing IIIII will always be slightly higher than the temperature of airflowing over and in contact with the exterior surfaces of f thermal bulb I25, so that the latter will always One of the factors to be considered in obtain ing a control which responds rapidly is the in-- ternal volume of the entire ex'pansible fluid thermostat of which the sensitive bulb forms a part. For a given transfer of heat to the sensiannealed copper and the sensitive bulb I25 is I bethe coldestpart of the thermostat system. It should be understood that the heater I45 increases and improves the responsiveness of the thermostat system asa whole and is utilized both during heating and cooling periods, and hence diflers' from the usual type of artificial heater heretofore provided in controls of this character inthat the latter are employed intermittently and not continuously and are utilized only during the heating periods to offset poor responsiveness by improving the sensitivity of'the control solely to terminate the heating period in accordance with a false room temperature.

In the control referred to above in which bellows Ill and I32 formed of beryllium-copper are employed, the capillary tube I30 is formed of soft 

